In a semiconductor device for electric power and the like, it is very important to efficiently dissipate heat generated in a power chip to an outside while ensuring a high insulation property. In order to enhance a heat dissipation capability, while it is preferable to reduce a thickness of an insulating layer on a lower side of a power chip, concerns are caused that reduction in a thickness of an insulating layer may degrade an insulation property.
Also, in a structure, a whole of which is full-molded with one kind of resin, a resin has more difficulties in running around an insulating-layer forming area as a thickness of an insulating layer is reduced, resulting in extremely degraded moldability, so that it is exceedingly difficult to reduce a thickness of an insulating layer. Therefore, there is no choice but to thicken an insulating layer to a certain degree, which causes degradation of heat dissipation property. In order to enhance a heat dissipation property while thickening an insulating layer to a certain degree, a resin having excellent thermal conductivity is used for an insulating layer. However, a resin having excellent thermal conductivity is expensive, and so, to use an expensive high-performance resin for an insulating layer including a part which does not need such a high-performance resin, would increase a manufacturing cost.
In view of the foregoing matters, for example, Patent Document 1 suggests a method in which both of ensured insulation and high heat dissipation can be easily achieved by using an insulating material which has a certain thickness and good thermal conductivity, for an insulating layer. This method, in which a high-performance insulating material is used only in a required part and immediately below a heat spreader, is advantageous also in terms of a manufacturing cost.
Like Patent Document 1, the following technique is developed in order to improve injectability of a resin into an area of an insulating layer immediately below a heat spreader. If injection of a resin immediately below a heat spreader is delayed, a weld is generated immediately below a heat spreader and a thickness of a resin is reduced due to a resin-injection pressure on an upper side of a heat spreader, resulting in occurrence of an insulation failure. By bending a lead frame vertically upward or providing a dam such as a notch in a front surface of a package, a function of a constriction part for regulating an injection amount of resin which is going to flow upward is provided, so that an amount of resin which flows into an insulating-layer forming area immediately below a heat spreader from a lower part of a lead frame is increased, to prevent generation of a weld immediately below a heat spreader.